METABOLISM & ENZYMES Flashcards
Week 5
What is metabolism?
All the chemical reactions take place in cells, and therefore in the organism of which the cells are a part.
What are the two types of chemical reactions metabolism is made up of?
- Catabolism
- Anabolism
What is catabolism?
The reactions in which large molecules are broken down into smaller ones, with the release of energy.
e.g. Digestion
What is anabolism?
The reactions in which small molecules are built into larger ones require energy.
e.g. protein synthesis
What is metabolism concerned with?
Maintaining a balance between energy release and energy utilisation.
What is a nutrient?
Any substance in food that is used for growth, repair, or maintaining the body; that is any substance required for metabolism.
What are the six groups of nutrients?
- Water
- Carbohydrates
- Lipids
- Proteins
- Minerals
- Vitamins
What are organic compounds? Provide three examples.
Molecules that have a carbon chain. They also contain a number of hydrogen atoms and may include atoms of oxygen, nitrogen and sulphur.
e.g. Carbs, proteins and lipids.
What are carbohydrates?
Organic molecules that are the main source of energy. They always contain carbon, hydrogen and oxygen.
What are monosaccharides?
Simple sugars or single-unit sugars
e.g. glucose, fructose, galactose
What are disaccharides?
Two simple sugars joined together.
e.g. sucrose, maltose, lactose.
What are polysaccharides?
Larger carbohydrate molecules form when many simple sugars join together.
e.g. glycogen, cellulose, starch
What are lipids?
Large organic molecules are made up of fatty acids and glycerol - an energy source.
What are proteins?
Organic compounds are made up of many amino acids.
e.g. enzymes.
What is nucleic acid?
Molecules containing nucleotides forming a chain; include ribonucleic acid (RNA) and deoxyribonucleic acid (DNA)
What are enzymes?
Biological catalysts speed up chemical reactions by lowering the activation energy. They are not consumed or altered in the reaction.
What is activation energy?
Reacting particles must collide with sufficient energy to break bonds and ensure the right atoms contact each other.
What is a substrate?
The molecule on which an enzyme acts.
Why is the enzyme so specific?
The enzyme and its substrate have complementary characteristics, and their shape and structure allow them to fit together.
What is an active site?
The part of the enzyme molecule that combines with the substrate.
What is an enzyme-substrate complex?
When the enzyme and substrate are combined.
What is the lock and key model?
States that the shape of the enzyme (the key) is always complementary to the shape of the substrate (the lock). Therefore, the two will fit exactly to form the enzyme-substrate complex.
What happens when an enzyme denatures?
The structure of the enzyme changes with extreme temperatures and pH. This changes the shape of the active site meaning the enzyme can no longer combine with the substrate.
What factors influence the enzyme activity and the rates of chemical reactions they are involved in?
- High enzyme and substrate concentration and temperature increase, speed up chemical reactions
- Reaction products must be removed continuously to maintain the reaction rate
- Enzymes are sensitive to pH; each has an optimum pH for effective functioning.
At what temperature does an enzyme denature?
Above 45-50 degrees enzymes can denature.
What is the optimum temperature for enzymes?
For most enzymes in the human body, this is 30-40 degrees Celsius.
What is the effect of enzymes influenced by?
Temperature, pH, the concentration of both the substrate and enzyme, the removal of products and the presence of cofactors, coenzymes and enzyme inhibitors.
